The 311 on Chicago's early phone numbers

There was a time when Chicagoans used numbers and letters to dial up friends. Maps didn’t hurt, either!

November 12, 2013

Jeffrey Osman of Chicago’s Bucktown neighborhood is sure of it. He remembers calling his friend Richie, a Humboldt Park resident, by dialing HUmboldt 6-5127. Translation on the telephone keypad: 486-5127.

Before 1977, Chicago phone numbers were often listed as Jeffrey remembers. The letters, which signified longer words, had once stood for exchanges — places where operators directed calls by plugging cords into switchboards with electric jacks that corresponded to individual telephone numbers.

Jeffrey’s recollection was strong, but the backstory nagged him — enough that he sent Curious City this question:

“What is the history behind the old telephone exchanges? For example, how did they get names like HUmboldt 6?”

What did we find after we dialed up the history of numbers and phone technology? Two big points. The first is that today’s smartphone users — the most savvy of which rarely even use phone numbers — may not realize there was a time when dialing pals required a working list of phone numbers and perhaps letters. It was also best to have a mental map of where contacts were physically located!

The other takeaway is that Chicago’s exchange names are more than interesting relics of an earlier time: They’re part of the city’s identity as a collection of neighborhoods.

Operator, please

Let’s go back to the beginning. Chicago’s first telephone exchange opened in 1878. Then, you actually told the operator the name and address you were trying to reach. Chicago’s first switchboards were at the telephone company’s central office downtown, and in two branches at Halsted Street and Canal Street.

Here’re a few significant dates in the evolution of telephone numbers:

Until 1923, a dialer would call an operator and ask for the person they wanted to reach by giving their exchange name or number. Phone numbers were just three or four digits, with an exchange name tacked onto the front. Names were sometimes selected to be memorable or easily understood over the phone. “CALUMET-555,” for example, could be taken from local Chicago geography.

In 1948 local exchange name codes shrunk to just two letters, making room for a fifth digit that would allow phone companies to meet growing demand for new numbers. When possible, the old exchange names were preserved — to continue the example above, Calumet became CAlumet 5. Some number combinations didn’t spell much at all, let alone a name that happened to have local significance. AT&T had national lists of recommended exchange names, so some of Chicago’s old exchange prefixes have nothing to do with the region.

But in Chicago, many subscribers were loath to give up their exchange names. It took until 1977 to fully phase out the system, and exchange names showed up in some Chicago phonebooks into the 1980s.

Local calls only

It’s probably no surprise that history buffs are interested in anything having to do with changing technology, but you may not realize that some small groups are dedicated enough to maintain databases of the names. One group — The Telephone EXchange Name Project — continues to accept new entries.